This non-provisional application claims priority under 35 U.S.C. § 119(a) from Korean Patent Application No. 2003-11898 filed on Feb. 26, 2003, which is herein incorporated by reference.
1. Field of the Invention
The present invention relates to methods of making a patterned film or a carbon nanotube composite using carbon nanotubes having polymerizable moieties on their surfaces. More specifically, the present invention relates to methods of making a carbon nanotube negative pattern or a polymerized carbon nanotube composite having interpenetrating polymer network by modifying the surfaces of the carbon nanotubes with polymerizable functional groups such as oxirane and anhydride groups and then subjecting the surface-modified carbon nanotubes either to a photolithography process or to a heatcuring process.
2. Description of the Related Art
Carbon nanotubes were found from electronmicroscopic observation by Dr. Iijima at Maijo University, Japan in 1991. Since then, carbon nanotubes have received profound studies. Typically, a carbon nanotube is like a hollow cylinder made of a graphite sheet, whose inner diameter ranges from 1 to 20 nm.
Graphite has been known to have a peculiar structure. That is, the covalent bonds between carbon atoms constituting graphite are arranged in an unusual style, so that graphite has a shape of rigid, flat hexagonal sheet. The upper and lower regions of the sheet are filled with dispersed free electrons, which keep translating in a parallel motion with the sheet. The graphite sheet rolls up in a spiral to generate a carbon nanotube, wherein curvatures of graphite sheet are coupled with those of the others. Electric properties of the carbon nanotube are in functional relation with the structure and diameter thereof (Phys. Rev. (1992) B46:1804 and Phys. Rev. Lett. (1992) 68:1579). Thus, an alteration of either helicity or chirality of the carbon nanotube results in a change of motion of the free electrons. Consequently, the free electrons are allowed to move freely as in a metallic material, or they have to overcome a barrier as in a semiconductive material. In this connection, the range of the barrier varies in concordance with the diameter of the carbon nanotube, and it may be 1 eV in case of the smallest tube. It is amazing that the identical material can have so various electric properties ranging from a conductor to a nonconductor according to its structure and diameter. These special characteristics of carbon nanotubes, including mechanical rigidity, chemical stability, variableness of electric conductivity and elongated hollow cylinder-like shape, makes the carbon nanotube useful for the production of flat-panel display (FPD), transistor, energy storing material, electronic devices of nano-size, and so on.
Recently, a method of arranging carbon nanotubes on a gold substrate was reported by Zhongfan Liu at Beijing University, the People's Republic of China, wherein every end of the carbon nanotube was modified with sulfur (Langmuir (2000) 16:3569). Another method was reported by Smalley at Rice University, U.S.A., wherein the method comprises the steps of: forming a self-assembled monolayer of trimethylsilyl groups on a silicon substrate; patterning the monolayer using electron beam; attaching amine groups to the pattern; and attaching carbon nanotubes to the amine groups (Chemical Physics Letters (1999) 303:125). However, this method is problematic in that the self-assembled monolayer of trimethylsilyl groups is unstable and susceptible to the circumstances.
Meanwhile, there has been reported a method of producing a polymer matrix composite by blending. 10–100 parts by weight of carbon nanotubes with 100 parts by weight polyvinyl alcohol, wherein thermal properties of the composite increased in proportion to the carbon nanotube content ((Adv. Mater. (1999) 11:937). However, this method is problematic in that such blending is insufficient to achieve good interface adhesiveness between carbon nanotubes and polyvinyl alcohol, so a surfactant is additionally needed. In this connection, there has been reported an example of enhancing the interface adhesiveness between carbon nanotubes and epoxy resins by the use of a certain surfactant (Chem. Mater. (2000) 12:1049).